Ergonomics and Cumulative Trauma Disorders
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Questions and Answers

What is the effect of deviated wrist postures on the carpal tunnel?

  • They increase tendon friction and compress the median nerve. (correct)
  • They have no impact on grip strength.
  • They increase the volume of the carpal tunnel.
  • They decrease tendon friction.

Increasing the frequency of repetitive tasks reduces the risk of cumulative trauma disorders.

False (B)

What grip type involves the thumb and one finger gripping an object?

Pad to pad grip (pinch grip)

The tendency for greater tension during work cycles results from increased _____ by the hands and fingers.

<p>force</p> Signup and view all the answers

Match the grip type with its description:

<p>Cylindrical grip = Fingers flexed around an object, thumb on one side Spherical grip = Fingers and thumb together around an object Tip to Tip grip = Tip of thumb against tip of a finger Lumbrical grip = MCP and PIP joint flexed while DIP is extended</p> Signup and view all the answers

What is a common symptom caused by direct impacts to the palm?

<p>Compression of the median nerve (A)</p> Signup and view all the answers

A hook grip involves extending the thumb and using fingers to grip an object.

<p>False (B)</p> Signup and view all the answers

What advantage does maintaining an upright neck position provide?

<p>Reduces fatigue in the neck (A)</p> Signup and view all the answers

When seated, loads on the lumbar spine are less than when standing.

<p>False (B)</p> Signup and view all the answers

What contributes to the risk of cumulative trauma disorders in relation to tool design?

<p>Improper design of the hand-held tool</p> Signup and view all the answers

What is the effect of tilting the head forward by 30° or more?

<p>Significant neck fatigue occurs rapidly.</p> Signup and view all the answers

To decrease disc loading in sitting workstations, one should use lumbar ______.

<p>support</p> Signup and view all the answers

Match the following workplace adjustments with their benefits:

<p>Standing workstation = Preserves the normal lordotic curve Sitting workstation with backrest angle over 90° = Decreases disc loading Using an anti-fatigue mat = Reduces physical body stresses Small downward slope of seat pan = Enhances proper spinal alignment</p> Signup and view all the answers

What are motorized handheld tools known for?

<p>Reducing the need for work cycle repetitions (A)</p> Signup and view all the answers

The posterior elements of the spine engage more when seated compared to standing.

<p>False (B)</p> Signup and view all the answers

What is an effective way to measure the neck flexion angle?

<p>By connecting a line from C7 to the tragus of the ear and comparing it with the vertical line passing through C7.</p> Signup and view all the answers

What is one benefit of floor mats in a workspace?

<p>They facilitate body sway and decrease ground reaction force. (D)</p> Signup and view all the answers

High-risk classifications require urgent implementation of risk reduction measures.

<p>True (A)</p> Signup and view all the answers

What interdisciplinary model is used to understand pain tolerance?

<p>Biopsychosocial model</p> Signup and view all the answers

Floor mats can help minimize fatigue by enhancing the pumping of blood through back muscles, thereby decreasing _____ .

<p>fatigue</p> Signup and view all the answers

Match the risk classification with its evaluation of tolerability:

<p>Very high = Unacceptable High = Acceptable Medium = Risks that should be reduced Low = Acceptable</p> Signup and view all the answers

In the risk classification table, what category represents risks that are considered acceptable with no further action needed?

<p>Very low (A)</p> Signup and view all the answers

Ground reaction force is associated with reducing blood flow through back muscles.

<p>False (B)</p> Signup and view all the answers

What measures should be taken for risks classified as ‘very high’?

<p>These risks should be deemed unacceptable, requiring immediate action.</p> Signup and view all the answers

What is the first step of risk control?

<p>Designing safety control measures (C)</p> Signup and view all the answers

Employers should never conduct a cost-benefit analysis when reducing risks.

<p>False (B)</p> Signup and view all the answers

Name one factor that must be considered when prioritizing safety control measures.

<p>The number of individuals exposed to the risk.</p> Signup and view all the answers

The implementation of prevention measures aims to reduce the likelihood of _____ occurrence.

<p>work accidents</p> Signup and view all the answers

Which of the following is NOT a type of safety control measure implementation?

<p>Restoration measures (A)</p> Signup and view all the answers

What should happen if risks cannot be eliminated?

<p>They should be reduced to an acceptable level.</p> Signup and view all the answers

Match the type of measures with their description:

<p>Prevention measures = Reduce likelihood of accidents Protection measures = Shield workers from risks Mitigation measures = Lessening impact of hazards</p> Signup and view all the answers

Additional safety measures may be necessary for workers with special needs.

<p>True (A)</p> Signup and view all the answers

Which of the following is a collective protection measure?

<p>Use of guards and physical barriers (C)</p> Signup and view all the answers

Individual protection measures should be prioritized over collective measures.

<p>False (B)</p> Signup and view all the answers

What is the purpose of mitigation measures in a workplace?

<p>To reduce the severity of damage and harm in the event of an accident.</p> Signup and view all the answers

According to the OSH Act, workers have the 'Right to Know' about the __________ they are exposed to.

<p>hazards</p> Signup and view all the answers

Match the following safety measures with their descriptions:

<p>Emergency plan = Prepared response for accidents Job rotation = Diminishing exposure duration Training courses = Legal requirement for risk awareness PPE = Individual protection against residual risks</p> Signup and view all the answers

Which of the following is NOT a part of organizational measures?

<p>Individual Personal Protective Equipment (PPE) (A)</p> Signup and view all the answers

Management monitoring is an essential part of promoting a safety culture in the workplace.

<p>True (A)</p> Signup and view all the answers

Name one example of a collective protection measure.

<p>Use of guards</p> Signup and view all the answers

What effect does a higher backrest angle combined with lumbar support have on the lumbar discs?

<p>Limits the force on the lumbar discs (D)</p> Signup and view all the answers

Sitting on a therapy ball can reduce the risk of fatigue in back muscles.

<p>True (A)</p> Signup and view all the answers

What is one mechanism to minimize back muscle fatigue throughout the day?

<p>Using foot rails to allow leg relaxation.</p> Signup and view all the answers

The __________ process can initiate a cumulative trauma sequence due to muscle fatigue.

<p>static overload</p> Signup and view all the answers

Match the following work environments with their potential impacts on back muscles:

<p>Auto assembly = Higher risk of muscular strains due to repetitive motions Food processing = Involves static loading of back muscles Therapy ball usage = Promotes balance and core strength Office work = May lead to poor posture and muscle fatigue</p> Signup and view all the answers

How can alternating legs placed on a foot rest impact back muscles?

<p>It helps minimize back muscle fatigue (A)</p> Signup and view all the answers

Hyper-extension of the trunk is a safe posture in the workplace.

<p>False (B)</p> Signup and view all the answers

What is the purpose of the 'LIFTMAX' black belt?

<p>To provide support and reduce strain on the back during lifting.</p> Signup and view all the answers

Flashcards

Assembly Line Platform Footrests

Standing on a platform with feet on a footrest, this design aims to reduce back fatigue and potentially reduce the risk of injury in assembly line workers.

Deviated Wrist Posture

A hand posture that deviates from the neutral wrist position can lead to a decrease in carpal tunnel space, increased tendon friction, median nerve compression, and reduced grip strength.

Repetitive Work Cycles

Repeating a work cycle frequently increases tendon friction and accelerates the progression of Cumulative Trauma Disorders (CTDs).

Forceful Hand Grips

Heavy lifting and forceful hand grips put more stress on the long tendons than the muscles, increasing the risk of CTDs.

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Contact Stress on the Median Nerve

The median nerve is vulnerable to compression and impact injuries. This can cause tingling, numbness, or pain in the hand.

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Power Grip

A power grip is when an object is held forcefully and then moved by the larger muscles in your arm. Think of lifting a heavy weight.

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Precision Grip

A precision grip uses fingers to manipulate an object. Think of writing or using a phone.

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Pad to Pad Grip (Pinch Grip)

A grip where you hold an object between your fingertips and thumb, like holding a pencil.

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Incorrect Grip Selection

Choosing an incorrect grip for a task or a tool that misaligns the wrist and hand can lead to CTDs.

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Power tools & strain

Power tools reduce physical strain and repetitive work cycles.

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Neck posture & disorders

Sustained neck postures can lead to neck disorders.

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Head tilt & fatigue

Tilting your head forward by 30 degrees or more causes significant neck fatigue.

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Neck flexion angle measurement

The intersection of a vertical line through C7 and a line connecting C7 to the tragus of the ear.

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Posterior spine & load

The spine's posterior elements are active when standing, helping to distribute load.

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Sitting & disc load

Sitting puts more load on the intervertebral discs than standing.

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Chair design & disc load

Increasing backrest angle, lumbar support, and a slight seat pan slope can reduce disc loading.

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Standing workstation & disc load

Maintaining a normal lumbar curve and using an anti-fatigue mat can reduce disc load while standing.

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Risk Control

The process of identifying and implementing safety measures to control risks.

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Design Safety Control Measures

The first step of risk control, aiming to eliminate risks completely or reduce them to an acceptable level.

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Implement Safety Control Measures

The implementation of safety measures after design, prioritizing prevention, then protection, and finally mitigation.

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Prevention Measures

Measures aimed at reducing the likelihood of work accidents or occupational diseases.

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Engineering or Technical Measures

Actions taken directly on the risk source to eliminate it, minimize its levels, or replace it with something safer.

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Remove the risk source

Ensure risks are 'designed out' of the workplace during the design phase.

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Reduce the levels of hazardous materials.

Reduce the levels of hazardous materials by implementing effective ventilation systems.

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Replace the risk source

Replace a dangerous element with a safer alternative.

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Backrest angle and disc force

The angle of the backrest influences the amount of force placed on the intervertebral discs in the lumbar region. A higher backrest angle and lumbar support reduce strain on the discs.

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Static muscle exertion

Static muscle exertion refers to holding a muscle in a fixed position for extended periods. This leads to decreased blood flow and increased risk of fatigue and injury.

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Muscle fatigue

When muscles are continuously contracted without rest, they can become fatigued. This weakens the muscles and increases the risk of injury.

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Foot rails and back muscle relaxation

Foot rails allow the back muscles to relax, improving blood flow and reducing muscle fatigue. Resting one leg on the foot rail allows the back muscles on that side to relax.

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Alternating leg resting

Alternating legs on the foot rest allows for alternating relaxation of back muscles, minimizing overall fatigue throughout the day.

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Hyper-extension of the trunk

Hyper-extension of the trunk is an exaggerated backward bending of the spine, putting excessive strain on the back muscles and discs.

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Cumulative trauma

Cumulative trauma is a condition that develops over time due to repetitive strain or stress on the body. It can affect the back muscles, discs, and joints.

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Lumbar support

Lumbar support helps to maintain the natural curve of the lower back, reducing stress on the discs and muscles.

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Substitution in Workplace Design

Replacing a risky material, equipment, or substance with a safer alternative during the design phase of the workplace.

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Collective Protection Measures

Protective measures designed to safeguard workers from hazards and reduce exposure to risks. These are implemented before individual protection and target the hazard at its source.

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Hazard Isolation

An example of collective protection measures that involves isolating the hazard using physical barriers, machinery guards, or remote handling techniques.

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Individual Protection Measures

Protective measures implemented after collective measures have been considered. These are individual actions taken by workers to mitigate residual risks.

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Mitigation Measures

Measures put in place to minimize the severity of harm to people, property, and the environment in the event of an accident or occupational disease.

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Emergency Plans

Procedures and resources designed to handle workplace accidents or emergencies effectively.

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Right to Know

A legal requirement under the OSH Act, this ensures workers are informed about the hazards they face, how these can affect them, and how to stay safe.

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Study Notes

Risk Factors for Cumulative Trauma Disorders (CTD)

  • Deviated wrist postures from neutral: reduce carpal tunnel volume, increasing tendon friction and compressing the median nerve; reduce grip strength due to altered muscle length-strength relationship.
  • Increased frequency/repetition of work cycle: increases friction within tendons, accelerating CTD progression.
  • Increased force during work cycle: greater force results in greater tendon tension, not muscle tension.
  • Direct impacts to the palm: impacts to the palm of the hand, causing compression and symptoms (contact stress). The median nerve runs near the palm.

Hand Grips

  • Power grip: used to hold and move objects forcefully; involves proximal muscles.
  • Precision grip: used to manipulate objects precisely; involves fingers.

Power Grips (Specific Types)

  • Cylindrical grip: fingers flexed around an object, thumb on one side, fingers on the other (e.g., gripping a hammer).
  • Spherical grip: fingers and thumb wrapped around an object (e.g., grabbing an apple).
  • Hook grip: second to fifth fingers flexed around an object in a hook-like manner. Thumb is not involved.
  • Lateral prehension: objects held between fingers (rarely used).

Precision Grips (Specific Types)

  • Pad-to-pad grip (pinch grip): involves thumb and one or more fingers (e.g., holding a pencil).
  • Tip-to-tip grip (pincer grip): involves tips of thumb and finger (e.g., picking up a coin).
  • Lumbrical grip (plate grip): MCP and PIP joints flexed; DIP extended; thumb opposes; used to hold horizontal objects like a plate.

Hand Grip and CTDs

  • CTDs can result from incorrect grip choices required by tasks or improper hand/wrist tool design.

Matched Anthropometry

  • Measurements of grip width (3.5" optimum / 1.5" min) and grip length (4.8") are relevant for correct hand/tool design relationship.

Motorized Hand Held Tools

  • Motorized tools help reduce physical stresses and repetition of work cycles.

The Neck

  • Neck disorders are associated with sustained work postures.
  • Upright neck positions reduce neck fatigue.
  • Forward head tilt (30° or more) significantly increases neck fatigue(increases the weight moment arm, thus requiring more muscle activation).

Measuring Neck Flexion Angle

  • Measured by the intersection of two lines: a vertical line through C7 (seventh cervical vertebra) and a line from C7 to the tragus of the ear.

Burden of Staring at a Smartphone

  • The effective weight on the spine increases with forward tilt. Quantified at different angles.

Visual Acuity in Chronic Neck Problems

  • Visual acuity should be assessed in individuals with chronic neck problems.

The Back

  • Anatomy of the spine (vertebral body, pedicle, facet joints, lamina, transverse/spinous processes). Associated curves (cervical, thoracic, lumbar, sacral)
  • The intervertebral disc anatomy.
  • Lumbar spine loads are higher during sitting compared to standing.
  • Spine load paths are different for seated vs. standing positions.

How to Decrease Disc Loading

  • Standing: maintain normal lumbar spine lordosis; use anti-fatigue mats.
  • Sitting: increase backrest angle over 90°; use lumbar support; use a small downward seat slope (10°).

Pain Tolerance (Biopsychosocial Model)

  • An interdisciplinary approach that considers the interplay between biology (physical health, genetic predispositions), psychology (coping skills, self-esteem), and social factors (family circumstances, social support) in pain tolerance.

Risk Classification and Guidance

  • Risk classification system identifies the priority level of risks (Very Low, Low, Medium, High, Very High).
  • Defines levels of acceptable risk based on tolerable and unacceptable risk tolerances.
  • Provides guidance for deciding necessary action and timescale (duration of intervention for a risk, resources)

Phase 3: Risk Control

  • Safety measures implementation is based on updated knowledge, good practice, and addresses worker health and safety needs, including those with special or additional requirements (pregnant women, young/aging workers, workers with disabilities).
  • This process should consider the number of individuals exposed when developing intervention timescales.

Design Safety Control Measures

  • The initial step is creating safety measures to eliminate risks, and reduce acceptable risks. The cost-benefit analysis should determine whether there is a cost-beneficial change.

Implementing Safety Control Measures (Hierarchy)

  • Risk control is a process that starts with prevention, then protection, and finally mitigation.

Prevention Measures

  • Removing risk.
  • Reducing risk substances.
  • Replacing risk materials, equipment, or substances (more effective during design phase)
  • Training on safety and awareness.
  • Appropriate worker procedures.
  • Maintaining good housekeeping

Protection Measures

  • Isolating hazards/risks.
  • Using physical barriers
  • Reducing exposure duration (e.g., job rotation).
  • Implementing safety signs and restricting entry.
  • Using PPE (personal protective equipment)

Mitigation Measures

  • Prepare when prevention / protection fails.
  • Recovery plans.
  • Emergency plans.
  • Evacuation planning and training.
  • Fire drills, tests, alarm systems, lights.
  • Return-to-work plans

Training and Information

  • Managers and workers need to be aware of the hazards and risks, and available training. OSH Act as the legal framework.
  • Legal requirement for information and training about workplace hazards and the harm they might cause and precautions to minimize those effects.

Phase 4: Review and Update

  • Regular review and update of risk management processes.
  • Ensuring implemented safety measures are adequate and effective.
  • Evaluating if improvements need to be made regarding new substances, equipment, or processes in the workplace.
  • Adapting risk controls based on new knowledge or emerging risks.

Documenting the Process

  • Documenting the risk management process is crucial. Should include
  • Work activities and areas being assessed.
  • At-risk employees.
  • List of occupational risks and hazards.
  • Likelihood and severity of potential harm.
  • Risk levels and acceptability.
  • Any control measures in place.

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Lecture 7: Ergonomics and Musculoskeletal Disorders PDF

Description

This quiz explores the impact of ergonomic practices on hand and wrist health, focusing on carpal tunnel syndrome and common workplace postures. Participants will assess their understanding of proper grip types, spinal loads, and preventive strategies against cumulative trauma disorders. Ideal for students and professionals in health and ergonomics.

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